
[1]. What was the IRT Ninth Avenue Line's extension?.
[2]. On September 17, 1879, the line was extended further north from 104th Street and Columbus Avenue, curved east at 110th Street, and then turned north onto Eighth Avenue to 125th Street..
[1]. What happened after it was extended?.
[2]. 
A new station at 116th Street, above Eighth Avenue, was opened.